What makes a Pink Diamond Pink?

Pink diamonds are completely unique in that they have no impurities to cause their color!?Most diamonds that have color (blue, yellow, etc) have their color due to impurities.?

Yellow diamonds are yellow from having additional nitrogen included during growth.?Nitrogen has an extra electron compared to carbon (5 vs 4), and this electron absorbs some of the blue light, leaving excess red and green coming out which blends to form yellow.?

Blue diamonds are blue due to boron being included during growth.?Boron only has three electrons, and the missing electron slot absorbs some of the red wavelengths, turning the diamond blue in appearance.

Pinks were originally tested searching for an impurity to explain what makes them pink, but none could ever be found.?This created a long time mystery in the diamond world as to what caused the obvious pink color.?

After extensive research it has been determined that the pink color comes from being grown in, or exposed to, exceptionally high pressure - well above that of what is present for white diamonds to grow.?At the atomic level, this creates alternating bands of compressed structure alternating with regular white (clear) diamond bands.?This is termed "twin planes".?It is the compressed bands interacting against the white planes that produce a unique structure that distinctly produce the actual pink color.?The pink is created because the structure at the junction between the twin planes absorb some of green from incoming white light, and thus create the attractive pink color of a true pink diamond.

The super high pressure required to form this alternating structure to make a pink diamond can come from seismic shock (i.e. sudden fault shifts or earthquakes) or volcanic explosions or similar, but the root cause of a pink diamonds 'pinkness' is the super high pressure shock it is formed under or exposed to.?

While all mined diamonds are formed under high pressure, pink diamonds are formed or exposed to a whole different level of super pressure. The compressed layers are up to 10x that present in a white diamond, indicative of exposure to massive amounts of pressure relative to ordinary white diamonds.

For lab grown pink diamonds, these are created by first growing a diamond via usual practice (HPHPT or CVD), and then a second step of running the diamond in secondary round of high pressure/high temperature to create the necessary pressure to turn create the unique structure that turns it pink.

This requirement for a diamond to be exposed to super high pressure may be part of the reason that pink diamonds are so rare.?It requires an exceptional event like a volcanic explosion to create the conditions necessary to produce a pink diamond, versus the conditions for white diamonds are much more common.